Alterations of fibrinolytic activity in human during and after hyperbaric oxygen exposure

To clarify the stage of fibrinolytic activation by hyperbaric oxygen (HBO) exposure, we examined its alterations in human during and after the HBO exposure. Eight healthy female volunteers breathed oxygen at 284 kPa (2.8 atmospheres absolute). Blood samples were collected before compression, shortly after compression to the pressure 284 kPa, shortly before the start of decompression, shortly after decompression, and then again 3 hours after decompression. We estimated the euglobulin fibrinolytic activity (EFA) and, the activities and antigens of both tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1). The PAI-1 activity and PAI-1 antigen showed significant decrease after compression to a pressure 284 kPa, before the start of decompression, and after decompression. The EFA level and t-PA activity rose significantly shortly after decompression, and 3 hours later returned on baseline. These findings suggest that fibrinolytic activity is elicited after HBO rather than during HBO.

[Health check on divers and compressed air workers]

We have conducted the health check of 3,554 compressed air workers and 1,821 divers, and also examined the incidence and severity of aseptic bone necrosis by using Roentgen pictures. We could classify 4,859 of 5,375 persons into four groups (A-D), based on our classification. We could also classify 4,205 of 5,375 persons that had had a bone X ray examination on the basis of the criteria described by Ota and Matsunaga (A-C). 4,859 persons belonged to four groups: class A (persons who can work, no limitations): 4,099 (84.4%), class B (persons who can work under conditions below 1.0 kg/cm2): 357 (7.3%), class C (persons who had better quit work under hyperbaric conditions, though they are not prohibited by regulations): 183 (3.8%), class D (persons who must be prohibited from working in a hyperbaric environment by laws of the Ministry of Labor): 88 (1.8%). About 90% of compressed air workers and divers (classes A and B) were permitted to work under hyperbaric conditions. Most of those belonging to classes C and D suffered from hypertension, cardiovascular disease and liver dysfunction. The incidence of aseptic bone necrosis was 11.1% (465 out of 4,205 persons). Eight persons (2.2%) belonged to criteria A which means poor prognosis. They were classified into class D. There is no differences between compressed air workers and divers in the incidence of aseptic bone necrosis.

[Saturation diving system at high altitude]

Practical saturation diving was firstly performed at high altitude in Japan in 1987. Its work was to change the screen which had covered the pipeline of a hydroelectric dam located 850 meters above sea level, the same operation had been conducted in 1992 and in 1993, 2 times each year (Total = 5 operations) after the work. The saturation dives have lasted from six to eight days on 4 occasions and 13 days (Total duration = 4075 minutes) on 1 occasion, since the initial pressurization until the end of the last decompression. In each operation, there had always been involved 3 divers. They have been compressed to an equivalent depth of 45-73m in the deck decompression chamber (DDC), briefed for work and transferred to the submersible decompression chamber (SDC), which was then submersed to 53-78m of depth. Wearing heated suit and breathing Heliox (both at the same temperature as the inside of the SDC), the divers have been locked out to perform their tasks, all monitored and supervised by the use of a remotely operated vehicle (ROV). The works have run uneventful and successfully until the end. The water temperature had been higher than the expected, i.e. 9-13 degrees C in all occasions. The inside conditions of the chamber had been the following: partial pressure of nitrogen was from 0.78 ATA; partial pressure of oxygen was from 0.35 to 0.40 ATA; partial pressure of carbon dioxide was less than 0.005 ATA; the inside temperature of the SDC was from 26 to 30 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)